Sorry about the delay, but I have been places with very restricted internet access for some time. I haven`t gone through the whole thread, but would like to add a few comments on lymphomas in general:
They are cancers involving immune (system) cells, and are well described in the Merck vet manual:
"Lymphomas are one of the most prevalent tumours in dogs and cats. The normal immune response requires a burst of rapid proliferation of lymphocytes. On occasion however, this proliferation may be uncontrolled, and lymphoid neoplasms result. Because lymphocytes are present in all organs, tumour development can occur in any organ. Lymphomas can be multicentric, mediastinal, gastrointestinal, renal, nervous, or leukemic. Less commonly, they occur in the eyes, skin, or nose. To determine the stage of the disease, CBC, serum chemistry profiles, abdominal ultrasound, abdominal radiographs, and bone marrow analyses are useful. Immuno-fluorescent staining can be performed in dogs and cats to characterize lymphomas. They may be either T cell or B cell in origin." and I`d also like to recommend the following link:
http://www.fabcats.org/owners/cancer/lymphoma.html
Lymphomas may be viral or unknown in origin or cause, but are often associated with use of immunosuppressive drugs. "Often" here means that when you have a cat with lymphoma, it may have been given an immunosuppressive drug before the lymphoma was seen, NOT the other way round! Most animals given immunosuppressive drugs do NOT develop lymphomas. But! They are caused by wildly replicating immune system cells, and some of them are difficult/impossible to treat, just like other cancers: you are better off without one, but you will often see successful treatment. Aggressive tumours in young animals are never a good thing, they are often discovered too late or they progress too quickly to respond to treatment. And as someone mentioned, congenital is not synonymous with inherited.
On a last note, a lot is unknown about cancers in general, and many people try to profit from this fact. Please, breathe through your nose when reading stuff on the internet proclaiming either "The TRUTH" or "The CURE" for cancers. Cross-check, and if you use
www.scholar.google.com you will find peer reviewed stuff that is less profit- and more fact-oriented.
per